/Engine/Plugins/Editor/UVEditor/Source/UVEditor/Public/UVEditorModeToolkit.h
For a specific tool palette category, construct and fill ToolbarBuilder with the category's tools
virtual void BuildToolPalette ( [FName](API\Runtime\Core\UObject\FName) PaletteName, class [FToolBarBuilder](API\Runtime\Slate\Framework\MultiBox\FToolBarBuilder) & ToolbarBuilder )